Re: perl-like string concatenation

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Mon, 09 Mar 2009 14:45:04 +0100
Message-ID:
<gp36hf$8k8$1@news.motzarella.org>
* James Kanze:

On Mar 9, 11:50 am, Christof Warlich <cwarl...@gmx.de> wrote:

James Kanze schrieb:

On Mar 9, 8:56 am, Christof Warlich <cwarl...@gmx.de> wrote:

is there any danger in overloading operator+ as follows:

template<typename T> string operator+(const string &x, T y) {
     ostringstream tmp;
     tmp << x << y;
     return tmp.str();
}


Only that it results in unreadable and unmaintainable code,
and that it's not really very useful.


Hmm... - why unreadable code? I'm writing a text processing
application where I quite frequently need to concatenate
strings from other strings, integers, characters, C character
strings, ..., so I found it much more readable to write
something like:

int i = 22;
string newString = string("Hello") + i + "whatever";


And what is that supposed to mean? Who knows what concatenating
an int to a string should mean: how many characters, what base,
etc.


Assuming for the sake of discussion that that is a problem, then isn't that a
problem also with e.g. std::ostringstream::operator<<?

I don't think such reasonable defaults are problematic.

On the contrary, having to specify every little customizable detail can IMHO be
very counter-productive, but it's my impression that it's almost impossible to
convince the IBM-oriented (e.g. Lotus Notes interface) and/or math-oriented
(e.g. C++0x random generators) and/or whatever-oriented guys that such extreme
verbosity is in conflict with goals like clarity, conciseness & correctness. And
in the other direction, it's almost impossible to convince some people that
having all kinds of implicit conversion (e.g. to char const* or to bool) is
ungood, that explicit code is better. But regarding that, a '+' is explicit.

Not that I think operator+ is good choice for building up strings, because its
natural semantics -- not the syntax -- are IMO unsuitable for this.

I've commented on that separate issue else-thread.

Cheers,

- Alf

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